Process for the recovery of coal resins with simultaneous partial desulphurisation of the coal



2,772,265 Patented Nov. 27, 1956 sists in subjecting powdered coal, e.g. 20-60 mesh British Standard Sieve, to the action of superheated steamat 2,772,265 subcarbonisation temperatures in the preferred temperaPROCESS FOR THE RECOVERY OF COAL RESINS 5 ff f P 319 l g WITHSIMULTANEOUS PARTIAL DESULPHURI- e W S 6P0 SATION OF THE COAL merlsedand chemically modrfied form, and can be collected by fractionalcondensation in liquld, semi-solid and Salimnzzaman Siddiqni, Karachi,Pakistan solid fractions, which can be subsequently employed in themanufacture of varnishes, enamels and other indus- No gf if ffg ggg 195410 trially useful products. Starting at a temperature of about 150 C.,the distillation of the resin proceeds more 5 Claims. (Cl. 260-107)vigorously from 200 C. onwards, and the operation is nearly completed in4 to 5 hours at 280 0:5 C. On

further treatment with superheated steam from 280 C.

This invention relates to the desulphurisation and imto 330 C. anadditional quantity of a solid dark resin provement of coals and to therecovery of coal resins and distils over. Preferably the coal ispreheated to about waxes therefrom. 100 C. before applying thesuperheated steam.

Some of the lignite and sub-bituminous coals carry Further, in theprocess briefly described above, part of varying proportions of resinousand waxy materials, ecothe sulphur which mainly occurs in most Pakistancoals nomic recovery of which can be of considerable industrial inorganically combined form and as pyritic sulphur, is value. Of the waxymaterials, an instance in point is the eliminated as H28, whichaccording to known processes Montan wax which occurs in some of theGerman brown can be either converted into elemental sulphur or sulcoals.Resins with properties similar to those of copal phuric acid. Thus, forexample, starting with coal concan be extracted from the Yallourna browncoal, and taining 3.6% of total sulphur an improved coal residue reddishto dark brown resins are further noted to occur Was obtained whichcontained only 2.5% of sulphur, and in some of the low-grade coals ofthe Indo-Pakistan was moreover lustrous and jet black in characterin'con-' sub-continent. trast to the dark brown, lustreless originalcoal powder,

The usual procedure employed for the recovery of i the calorific valueof the residue being 12,411 as against resins and waxes from coals isbased on solvent extrac- 12,168 of the original. On continued heatingbelow the tion, which because of the costs involved andnon-availtemperature range of active decomposition of the coal abilityof the solvents in the industrially under-developed substance at 300 C.to 330 C., the sulphur content is countries is often not a feasibleeconomic proposition. progressively reduced to below 1%,tl1e time ofheating A way out of this difirculty has been sought in the electroverylargely depending on the intimate contact of the coal static separationof the resin from the crushed coal mateparticles with superheated steam.rial, taking advantage of the difierence in the electrical With the helpof the present invention, therefore, not properties of the coal and theresin. This process, howonly are the resins and waxes obtained in anindustrially ever, is not practicable in all cases, and mostly yieldsthe useful form, but the coal is appreciably improved through resinmixed with quite large quantities of coal, necessitatthe partialelimination of sulphur, high content of which ing its subsequentextraction with solvents. is a great draw-back for various industrialuses of the In the course of investigations on the low grade sulphur- 0coal. From the following comparison of the analytical bearing coals ofWestern Pakistan, the occurrence of a data of the original and treatedcoal in the cited example fairly high percentage of resin (ranging up to10%) has relating to 10 hours of heating, it will be further observedbeen noted in some of them, particularly in the nonthat the coal is alsogenerally improved. by the process to which the present inventionrelates:

Volatile Fixed Calorific Moisture, matter, Ash, percarbon, Sulphur,value, Remarks percent percent cent percent percent t. u.s

per 1b.

Original coal powder 3. l 38. 6 7. 9 50. 4 3. 6 12, 168 Treated coalresidue... 2.0 5. 5 12.7 79.9 2. 5 12, 411 100 parts of coal powderyielded 82.7 parts of the coal residue, and a total of 8.2 parts ofmodified resin.

coking coal from the Makerwal area in the Punjab. This Analytical dataof the coal residues, relating to the resin can be extracted with thehelp of mixed organic superheated steam treatment of coals for periodsof 10 solvents like benzene and chloroform, but for the reasons alreadystated its solvent extraction is not practicable.

The process to which the present invention relates conand 20 hours andof the original coal are given in the following table and this datasubstantiates the points discussed above.

TABLE Proximate analysis, as received Ultimate analysis, moisture freebasis basis Calorific value (net) Remarks Mois- Volatile Fixed Ash, 0, IN, S, O, B. t. u.s ture, matter, carbon, percent percent percent percentpercent percent per 1b. percent percent percent Makcrwal (Punjab)Goal 1. Original coal powder. 5.0 40.8 44.6 9.0 69.8 4.9 1.3 4. 2 11.711,896

Coal residue al't- 5.3 8.3 72.9 15.9 74. 5 2.1 1.2 3.1 3.1 12, 089 100parts of coal powder or hours yielded 79.1 parts of the treatment withcoal residue, and a total superheated of 9.7 parts of modified steam.resin and waxy products on moisture-free basis.

Coal residue ait- 2.8 7.6 74.2 15.9 75.0 1.9 1.2 2.8 3.3 12,154 100parts of coal powder er hours yielded 78.5 parts of the treatment. coalresidue and a total of 10.3 parts of modified resin and waxy products onmoisture-free basis. Metmg (Smd) Coat 22. Original coal powder. 20. 744. 5 20. 4 14. 6 57. 1 4. 72 1. 2 2. 48 19. 9 9, 686

Coal residue aft- 3.2 14. 5 58.69 23. 73 63.8 2. 43 1.31 1.67 7.0610,771 100 parts of coal powder or 10 hours yielded a total of 76.5treatment. parts of the coal residue and a total of 7.4. parts ofmodified resin and waxy products on moisturefree basis.

Coal residue ait- 4.4 7.7 58. 68 29.3 65.5 1.35 0.88 0.87 2.08 11, 23100 parts of coal residue er 20 hours yielded 71.1 parts of thetreatment. coal residue and a total of 7.8 parts of modified resin andwaxy products on moisture-free basis.

The following example will serve to illustrate the invention but is notto be regarded as limiting it in any way.

Example One kilogram of powdered Makerwal coal was indirectly preheatedto about 100 C. in a retort provided with steam inlet, temperaturerecording arrangement, and an outlet into a fractional condensationsystem of three receivers, the first two fitted with a water-cooledcondenser, the depth of the coal bed being of the order of 4".superheated steam was then led into the retort, taking the temperatureto 280 C. and maintaining it at that level :5" C. In the process ofheating under these conditions copious fumes, carrying depolymeriscdresin and waxy material started to evolve at about 160 C. In about 4hours the distillation of depolymerised resin was nearly complete, thedark solid fraction of it collecting in the first, the middle fractionin the second and the lighter fraction in the third receiver. Thetemperature of the steam was subsequently increased to 300 C.- -5 C.

and the steam treatment continued for 6 hours longer. In the course ofthis period, a further quantity of a dark solid product distilled overand the coal was progressively desulphurised with the evolution of H28.The coal residue obtained after this treatment was of a jet blacklustrous character and formed 79.1% of the original coal, on amoisture-free basis. The total weight of the distilled depolymeriscdresin freed of moisture was 9.7% on the weight of the coal on amoisture-free basis.

What I claim is:

1. A process for the recovery of resins and waxes from coal withsimultaneous desulphurisation and improvement of the coal, whichconsists in subjecting powdered coal to the action of superheated steamat a sub-carbonisation temperature range of the coals, and preferably at200 C. to 330 C.

2. A process as claimed in claim 1, wherein the coal employed for thesuperheated steam treatment is powdered to the preferred particle sizeof range of 2060 mesh B. S. S.

3. A process as claimed in claim 1 wherein the powdered coal mass ispreheated to about C. before being subjected to superheated steamtreatment.

4. A process as claimed in claim 1 wherein the powdered coal mass issubjected to superheated steam treatment at temperatures above 280 C.but below the temperature range of active decomposition of coal mass,and is then treated with superheated steam in the temperature range of300 C. to 330 C.

5. A process as claimed in claim 1 wherein the depolymerised resindistilling over with the superheated steam is collected by fractionalcondensation in semisolid, liquid and lighter oily fractions.

References Cited in the file of this patent UNITED STATES PATENTS 57,304Esty Aug. 21, 1866 FOREIGN PATENTS 325,816 Great Britain Feb. 27, 1930

1. A PROCESS FOR THE RECOVERY OF RESINS AND WAXES FROM COAL WITH SIMULTANEOUS DESULPHURISATION AND IMPROVEMENT OF THE COAL, WHICH CONSISTS IN SUBJECTING POWDERED COAL TO THE ACTION OF SUPERHEATED STEAM AT A SUB-CARBONISATION TEMPERATURE RANGE OF THE COALS, AND PREFERABLY AT 200* C. TO 330* C. 